Trucking is the primary mode of long-distance and short-haul transport for goods and materials in the United States, and many other countries. Trucks typically include a motorized cab in which the driver sits and operates the vehicle. The cab is attached to a box-like cargo section. Smaller trucks typically include an integral cargo section that sits on a unified frame which extends from the front wheels to the rear wheel assembly. Larger trucks often include a detachable cab unit with multiple driven axles, and a separate trailer with a long box-like cargo unit seated atop two or more sets of wheel assemblies. These truck assemblages are commonly referred to as “semi-trailers” or “tractor trailers.” Most modern trucks' cabs, particularly those of tractor trailers, have been fitted with aerodynamic fairings on their roof, sides and front. Among other things, these fairings assist in directing air over the exposed top of the box-like cargo body, which typically extends higher (by several feet) than the average cab roof. The flat, projecting front face of a cargo body is a substantial source of drag. The use of such front-mounted aerodynamic fairings in recent years has significantly lowered drag and, therefore, raised fuel economy for trucks, especially those traveling at high speed on open highways.
However, the rear end of the truck's cargo body has remained the same throughout its history. This is mainly because most trucks include large swinging or rolling doors on their rear face. Trucks may also include a lift gate or a lip that is suited particularly to backing the truck into a loading dock area so that goods can be unloaded from the cargo body. It is well-known that the provision of appropriate aerodynamic fairings (typically including an inwardly tapered set of walls) would further reduce the aerodynamic profile of the truck by reducing drag at the rear face. The reduction of drag, in turn, increases fuel economy.
Nevertheless, most attempts to provide aerodynamic structures that integrate with the structure and function of the rear cargo doors of a truck have been unsuccessful and/or impractical to use and operate. Such rear aerodynamic structures are typically large and difficult to remove from the rear to provide access to the cargo doors when needed. One approach is to provide a structure that swings upwardly, completely out of the path of the doors. However, aerodynamic structures that swing upwardly require substantial strength or force to be moved away from the doors, and also require substantial height clearance above an already tall cargo body. Other solutions have attempted to provide an aerodynamic structure that hinges to one side of the cargo body. While this approach requires less force to move, it also requires substantial side clearance—which is generally absent from a closely packed, multi-truck loading dock.
For useful background information on aerodynamic structures for swinging cargo doors, refer to commonly assigned U.S. Pat. No. 8,100,461, issued Jan. 24, 2012, by Smith et al., and U.S. Pat. No. 8,360,509, issued Jan. 29, 2013, by Smith et al., which are both incorporated herein by reference in their entireties for all purposes. Among other things, these patents describe various structures that provide deployable rear aerodynamic structures to swinging cargo body rear doors. Notably, these structures allow the aerodynamic panels to be folded against the door in a retracted position so the door can be opened normally (swung to the side of the cargo body). The panels are deployed when the vehicle moves at highway speed. Various actuators, both manually operated and powered, move the doors between the retracted and the deployed positions. The panels can be joined together with a variety of hinged folding arrangements (e.g., a diagonal hinge running across each top panel) so that the panels deploy (unfold) and/or retract (fold) concurrently. Linkages, such as swingarm structures, can be used to tie the top and side panels together and assist in concurrent motion between retracted and deployed positions.